What is the biggest earthquake fault line?

Answers

It hard to chose an exact “line” as each one is just where two tectonic plates meet, and every fault “line” is connected to another. However, different sections of these lines have different names. The one that is commonly heard of in the U.S. is the San Andreas fault line which is the intersection of the North American plate with the Pacific plate that borders the west coast.

In addition, the longest rupture of a fault line was during the Sumatra-Andaman earthquake that was 720 to 780 miles or 1,200 to 1,300 kilometers.*More information can be found in the link below.

Below is an image of all the fault lines throughout the world. Also notice that it shows different places where there are convergent and divergent plates.

The second citation is a google map of the San Andreas fault line, complete with a view of the cities that lie along its faulty-faultness. The first is the website that used google maps to google map the fault!

Note that the map shown does not show “all the fault lines throughout the world.” There are tens of thousands of faults all over the planet. What that map shows is plate boundaries. These are, indeed, the locations for the great majority of earthquakes, but by no means all. A great many earthquakes, including very intense and devastating ones, occur hundreds and thousands of miles away from the lines on that map.

As has been said, there are fault lines all over the world (places where the plates meet). It doesn’t quite make sense to discuss the biggest line; instead, it is the amount of pressure two plates are creating as they try to slide past each other that creates the magnitude of the quakes.

According to the USGS, scientists are able to predict roughly where and earthquake is likely, and what magnitude is expected. Predicting when it will happen is very difficult though.

The links below discuss how earthquakes happen (link 1) and the specifics of the earthquake in Japan in March of 2011.

An 8.9 magnitude earthquake hit Japan today, Friday March 11, 2011, the largest quake ever to hit that country since the creation of the seismograph. It is among the top ten earthquakes ever recorded in the world. It’s magnitude was 8.9 (out of 10). The corresponding tsunami caused by this earthquake has created as yet uncalculated damage to life and infrastructure, but the death toll so far is in the hundreds. Japan is on a red alert for economic losses due to widespread damage. Follow the link below for a more detailed estimate of losses.

How do earthquakes cause tsunamis? When tectonic plates shift on the ocean floor, the above lying water is displaced from its original state of equilibrium. Enormous waves form under the force of gravity as the displaced water tries to regain its equilibrium.

Along which fault was this earthquake? This quake was in the Japan Trench, where the Pacific tectonic plate slides under the Japan plate.

How is magnitude determined? Earthquakes are measured on the Richter scale, invented by Charles F. Richter in 1934. An earthquakes rating is based on the highest wave the earthquake produces, as registered on a seismograph. Most earthquakes only rate at 2.5 or less.

The largest earthquake ever recorded (since the creation of the seismograph) occurred in Chile in May of 1960. It had a magnitude of 9.5. Follow the link below to find a list of major earthquakes.

Magnitude is determined PRIMARILY on the amount of damage they have/will cause.
Thus the more non-earthquake proof buildings along the fault line, the greater the magnitude when it comes.
The strength of the wave plays into it, but so does the amount of damage that quake is likely to cause.

Actually the most used magnitude scale, the moment magnitude, is completely unrelated to damage, as is the older Richter scale, because damage is subjective and depends on many things besides the power of the earthquake. The qualitative Mercalli scale is a relatively subjective scale based on human perceptions and including damage. A Mercalli magnitude of XII (“total destruction”) might correlate with a 7.0 on the quantitative scales.

It appears to be a continuous stretch, the ends of which will rub against one another, just as a volcanic explosion will trigger an earthquake elsewhere (oh that’s right, that doesn’t happen either, does it?)
And I specified it APPEARED to be from the poor quality of the map that was posted in answer to the querant’s question.

The New Madrid seismic zone have been known to cause the biggest earthquake disasters in 1811-1812. The fault line in New Madrid connects major plates together to near the souther midwest United States stretching southwest from New Madrid, Missouri.

In 1811-1812 the New Madrid earthquake caused one of the biggest earthquakes in the eastern United States in all of history. This earthquake have been known to widen the Mississippi river today! This earth quake have cause a seies of 4 other earthquakes from 1811-1812.

According to United States Geological Survey:

December 16, 1811, 0815 UTC (2:15 a.m.); (M ~7.2 – 8.1[2]) epicenter in northeast Arkansas. It caused only slight damage to man-made structures, mainly because of the sparse population in the epicentral area. The future location of Memphis, Tennessee experienced level IX shaking on the Mercalli intensity scale. A seismic seiche propagated upriver, and Little Prairie (a village that was on the site of the former Fort San Fernando, near the site of present-day Caruthersville, Missouri) was heavily damaged by soil liquefaction.[3]

December 16, 1811, 1415 UTC (8:15 a.m.); (M ~7.2–8.1) epicenter in northeast Arkansas. This shock followed the first earthquake by six hours and was similar in intensity.[2]

January 23, 1812, 1500 UTC (9 a.m.); (M ~7.0–7.8[2]) epicenter in the Missouri Bootheel. The meizoseismal area was characterized by general ground warping, ejections, fissuring, severe landslides, and caving of stream banks. Johnson and Schweig attributed this earthquake to a rupture on the New Madrid North Fault. This may have placed strain on the Reelfoot Fault.[3]

February 7, 1812, 0945 UTC (4:45 a.m.); (M ~7.4–8.0[2]) epicenter near New Madrid, Missouri. New Madrid was destroyed. At St. Louis, Missouri, many houses were severely damaged, and their chimneys were toppled. This shock was definitively attributed to the Reelfoot Fault by Johnston and Schweig. Uplift along a segment of this reverse fault created temporary waterfalls on the Mississippi at Kentucky Bend, created waves that propagated upstream, and caused the formation of Reelfoot Lake by obstructing streams in what is now Lake County, Tennessee.[3]